I. Field of the Invention
This invention relates generally to an apparatus and related method for controlling the lighting direction of a light source. More specifically, this invention relates to an apparatus and related method for controlling the lighting direction of a vehicle headlamp which can be set to either a low beam state or a high beam state.
II. Backqround Information
As is generally known, automobiles are typically equipped with vehicle headlamps which may be switched between a low beam state and a high beam state. The switching device used to switch the headlamps between low beam and high beam states is referred to as a dimmer switch. With the recent increasing use of electronic control circuits for controlling automobile devices, it has been proposed to use such a circuit to improve the switching of headlamp lighting directions.
For example, electronic control circuitry may be used so that the dimmer switch functions merely to generate a command signal which causes a change in the lighting direction of the vehicle headlamps from the high beam state to the low beam state or vice versa. The electronic control circuit causes the headlamps to emit light in a different direction from the previous direction each time the dimmer switch is turned ON. In such a manner, the operator of an automobile, upon observing the need for a change in lighting direction may achieve the change by merely turning ON the dimmer switch, thus causing a command signal to be received by the electronic control circuit from the dimmer switch. The automobile operator need not decide which way to move the dimmer switch since the dimmer switch is turned ON to change the lighting direction from a current lighting direction, whatever it may be. The dimmer switch may be of the momentary kind, set to be turned OFF shortly after it has been turned ON.
The use of a dimmer switch merely to alternate the lighting direction of the headlamps creates an arrangement whereby the lighting direction of the headlamps, as stored by the electronic control circuit, may reside either in the low beam or high beam state when another switch, which is generally used to turn the headlamps ON and OFF, is turned OFF and then back ON. Accordingly, at the time the headlamps are turned ON, they may emit light in either the low beam or high beam state. It is not desirable, however, that the headlamps be turned ON to operate immediately in the high beam state. With apparatus as described above, the possibility exists, and it will often happen, that the operator of an automobile will put his headlamps ON in the face of oncoming automobile traffic, and that, unknown to the automobile driver and very much to the dismay of the oncoming drivers, the headlamps would have been set to emit light in the high beam direction. Oncoming drivers are very likely to be dazzled by such high beam-directed light.
That the foregoing possibility of dazzlement exists when an electronic control circuit is being used to control the dimmer switch means that the electronic control circuitry may be more fully used to simplify the use of the dimmer switch.